turn a new leaf的用法和样例：
- As flowers unfold and life renews, it is hard to imagine a more perfect setting for smokers to turn a new leaf and quit smoking.
- I want to settle down,and turn over a new leaf.
- The completion of the Airport Railway also turns a new leaf in our history of railway development.
- Do you promise to turn over a new leaf.
- He decided to turn over a new leaf.
- But they must turn over a new leaf.